/**
 * URL方式保存文件到本地
 * @param data 文件的blob数据
 * @param name 文件名
 */
function saveAs(data, name) {
    const urlObject = window.URL || window.webkitURL || window
    const export_blob = new Blob([data])
    const save_link = document.createElement('a')
    save_link.href = urlObject.createObjectURL(export_blob)
    save_link.download = name
    save_link.click()
    urlObject.revokeObjectURL(save_link.href)
}

/**
 * 根据文件url获取文件名
 * @param url 文件url
 */
function getFileName(url) {
    const num = url.lastIndexOf('/') + 1
    let fileName = url.substring(num)
    //把参数和文件名分割开
    fileName = decodeURI(fileName.split('?')[0])
    return fileName
}

/**
 * 根据文件地址下载文件
 * @param {*} sUrl
 */
export function downloadByUrl({ url, target = '_blank', fileName }: {
    url: string
    target?: '_self' | '_blank'
    fileName?: string
}): Promise<boolean> {
    // 是否同源
    const isSameHost = new URL(url).host == location.host
    return new Promise<boolean>((resolve, reject) => {
        if (isSameHost) {
            const link = document.createElement('a')
            link.href = url
            link.target = target

            if (link.download !== undefined) {
                link.download = fileName || getFileName(url)
            }

            if (document.createEvent) {
                const e = document.createEvent('MouseEvents')
                e.initEvent('click', true, true)
                link.dispatchEvent(e)
                return resolve(true)
            }

            if (url.indexOf('?') === -1) {
                url += '?download'
            }

            window.open(url, target)
            return resolve(true)
        } else {
            const canvas = document.createElement('canvas')
            const img = document.createElement('img')
            img.setAttribute('crossOrigin', 'Anonymous')
            img.src = url
            img.onload = (e) => {
                canvas.width = img.width
                canvas.height = img.height
                const context = canvas.getContext('2d')!
                context.drawImage(img, 0, 0, img.width, img.height)
                // window.navigator.msSaveBlob(canvas.msToBlob(),'image.jpg');
                // saveAs(imageDataUrl, '附件');
                canvas.toBlob((blob) => {
                    const link = document.createElement('a')
                    link.href = window.URL.createObjectURL(blob)
                    link.download = getFileName(url)
                    link.click()
                    URL.revokeObjectURL(link.href)
                    resolve(true)
                }, 'image/jpeg')
            }
            img.onerror = (e) => reject(e)
        }
    })
}
